Sulfatopropionamid and preparation of acrylic acid



Patented Aug. 12, 1947 UNITED STATES SULFATOPROPIONAMID AND PREPARA- TION OF ACRYLIC ACID Harold S. Davis, Greenwich, 01d Greenwich, and John Myrl Lichtenwalter, G. Erickson, Greenwich, Conn, assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application May 14, 1945,

Serial No. 593,774

13 Claims. (01. 260-458) 1 I 2 The present invention relates to a method of furic acid to produce fi-sulfatopropionamide in preparing acrylic acid. Heretofore it has been proposed to produce acrylic acid by heating ethylene cyanohydrin substantially quantitative yields. on the contrary, when the sulfuric acid contains substantial quantities of water, its reactivity toward ethylene with sulfuric acid and water. The direct hy- 5 cyanohydrin' is greatly decreased and even after drolysis of the cyanohydrin with aqueous sulprolonged treatment unchanged ethylene cyanofuric acid by this known method is an extremely hydrin can be isolated from the overall reaction hazardous procedure. The reaction is diflicult product. to control and the yields of acrylic acid are in- I In carrying out the process, the ethylene cyanoconsistent. hydrin and anhydrous sulfuric acid are mixed It has now been discovered that acrylic acid together, preferably by slowly adding the cyanomaybe prepared in a simple and convenient manhydrin to the acid with good stirring. Th temner by reacting ethylene cyanohydrin withanperature of the reaction mixture is not allowed hydrous sulfuric acid to produce p-sulfatoproto exceed about 100 0., and is maintained prefpionamide, adding water thereto, heating the 1 e ab y it in t e an e of 40-9D C. The sulmixture at a temperature sufficient; to form furic acid may be used in excess of one mol of acrylic acid and ammonium bisulfate, and dis- Cya y 1 One 11101 of acid depending 0n tilling the acrylic acid therefrom. the desired fluidity of the product. Water is The reactions involved in the preparati n f then added to the reaction menstruum with stiracrylic acid according to the present invention ring to hydroly e e fif t p p de The may be outlined as follows:

011.:012100011 Nmnso.

resulting mixture is heated until hydrolysis of the amide group is substantially complete, followed by distillation of the product preferably under reduced pressure. Acrylic acid along with water, the latter corresponding approximately to the excess used in the hydrolysis step, distills over and iscondensed by cooling.

In the reaction of ethylene cyanohydrin with anhydrous sulfuric acid, it will be seen that one equivalent of free acid disappears as the p-s'ulfatopropionamide is formed. It has been found that the SO4H group is not easily hydrolyzed. Accordingly, it is possible to follow the progress of the reaction with time by dissolving weighed samples of.the product in water and titrating them with standard alkali. The examples given in Table 1 illustrate the progress of the reaction with time for various molar ratios of acid to cyanohydrin at difierent temperatures.

Table 1 [Percentage of Ethylene Oyanohydrin Reacted] Time is from start or addition of cyanog g gi g hydrin to acid. Completion oi addi- F mmple Acid to Temp tlon required 16-20 minutes Period when solidification of product Ethylene C. appeared, Minutes Cyamhydrm 20 Min. 30 Min. 1 Hour 2 Hours Per cent Per cent Per cent Per cent 1 62. 5 63. 5 65. 6 67. 5 150. l 68.0 72. 8 77. 7 84.0 45. 1 67. 8 .69. 8 81. 0 84. 0 40. l 80 77. 1 85. 2 20. 1.25 60 81. 2 86. 1 40. 1. 5 40 81. 8 83. 4 120. l. 5 60 89. 5 93. 3 40. 1.5 80 94. 8 98. 3 23. l. 60 92. 8 96. 2 Semidiuid at room temp. 2 40 92. 6 96.1 Fluid at room temp. for one week. 2 60 95. 8 98. 0 Fluid at room temp. for one week.

- from the start of the addition of the cyanohydrin. The reaction rate increases with the molar ratio of acid to cyanohydrin and with the temperature. In Example 11 when using a molar ratio of 2, reaction was 95.8% complete at 60 C. by the time all the cyanohydrin had been added to the acid. The reaction products tend to solidify indicating that the fl-sulfatopropionamide is not soluble in all proportions in anhydrous sulfuric acid. This tendency decreases with the molar ratio of acid to cyanohydrin. The solid material which separates from the products is p-sulfatopropionamide. I

A reaction product, made with a molar ratio dried in a. vacuum oven at 5060 C. for 48 hours. The analytical results on the two samples were as follows:

Acid N SO: Equivalence Per cent Per cent Per cent Calculated for HOlSCHlCHiCONHi. 8.28 47.33 100 Found in sample thoroughly centriiuged 7.97 105.5 Found in sample thoroughly centriiuged and alcohol washed 8. 28 47. 100. 8

fl-sulfatopropionamide is a new compound. It

ten at about 110 C. and gradually between 160 and 180 C.

The efiect of time at various temperatures of hydrolysis on the yield of acrylic acid is illustrated becomes liquid v of 2 (1 ethylene cyanohydrin:2 sulfuric acid). deby the examples in Table 2.

Table 2 Per cent Per cent Ex 18 Mols Mols Mols g zfi fij f" Time of Distillation Yield Acrylic 5 E011 also. Hi0 fi Hydrolysis Press., mm. Acrylic Acid in Acid. Distillate 1 2 1 120 4111's l2-l5 76 89.6 1 2 l 120 19 hrs 12-15 76.7 93.6 1 2 2 120 4 hrs- 12-15 91.6 77.1 1 2 2 120 6 hrs 12-15 92.9 75 1 2 2 120 19 hrs 12-15 87.3 76.2 1 2 2 106 4hr 12-15 14.9 79.1 1 2 2 100 6 hi 12-15 79.9 74.5 1 2 2 165 15 min 12 91.2 16.9 1 2 2 155 10 min 25 9o 76. 5 1 2 2 155 20min 90.5 79.6 1 2 a 155 10 min 25 91.6 68.8 1 2 a 155 20min 20 92.3 65.1 1 2 3 155 36 min 12 94.9 65.6 1 2 2 155 15 min 760 71 77 1 2 2 distilled directl 760 7c 92. 4 l 2 3 distilled directly 760 84 69. 8

posited white crystals after standing three weeks. The crystals were removed and thoroughly centrifuged to remove most oi. the adhering H2801,

The effect of varying the amount of water used in the hydrolysis step on the yield of acrylic acid is illustrated by the examples listed in Table 3.

Table 3 Per cent Per cent Exam 18s Mols Mols Mole gg gg g Time of Distillation Yield Acrylic P ECH also. Hi0 c Hydrolysis Presa, mm. Acrylic Acid in Acid Distillate Hours 1 1. 7a 1.5 120 6 12-15 91.2 83.6 1 1. 75 2. 0 120 6 12-15 90. 4 76.0 1 1. 7s a. o 120 4 12-15 93. s 65.0 1 2 1 120 4 12-15 76.0 89.6 1 2 2 120 4 12-15 91.6 77.1 1 2 3 120 4 12-15 93. 2 65.6 1 2 4 120 4 12-15 96.0 56.8 1 2 2 distilled directly 760 76 82. 4 1 2. s distilled directly 760 s4 69. 9 1 2 4 distilled directly 190 99 61.3

and a sample analyzed for total nitrogen, sulfur, and acid equivalence. The white crystalline material was then washed several times on a. sintered-glass filter funnel with z-B-ethanol, and

The examples given in Table 4 show the effect of varying the amount of anhydrous sulfuric acid in the formation of .B-sulfatopropionamide on the yield of acrylic acid.

Table 4 Per cent Per cent Exam leg M015 M015 M015 fig flj f Time of Distillation Yield Acrylic p E011 B250 1120 t Hydrolysis Press., mm. Acrylic Acid in Acid Distillate Hours 1 1. 25 2 1%) 3 12-15 84. 2 69.8 1 1. 2 120 4 12-15 86. 8 75. 6 1 1. 2 4 12-15 91. 2 76. 5 1 2 2 120 4 12-15 93. 3 79.0

5. The influence of distillation pressure on the yield of acrylic acid is illustrated by the examples listed in Table 5.

includes the steps of reacting ethylene cyanohydrin with anhydrous sulfuric acid to produce p-sulfatopropionamide, adding water thereto,

Table Per cent Per cent E l M015 M015 M015 $93 1? I Time of Distillation Yield Acrylic 95 ECH H25 04 "B mre o Hydrolysis Press, mm. Acrylic Acid in Acid Distillate Minutes 1 2 2 155 3 94. 2 77. 4 1 2 2 155 15 12 91. 2 7c. 9 1 2 2 155 10 90. 0 76. 5 1 2 2 155 15 50 89.6 77. 3 1 2 2 155 15 100 89. 6 79. 7 1 2 2 155 15 180 88. 5 79.7 1 2 2 155 15 760 71.0 77.0 1 2 3 155 15 3 100. 0 B4. 2 1 2 3 155 15 13 c4. 8 63. 6 1 2 3 155 15 5O 96. 7 67. 2 1 2 3 155 15 100 96. 9 68. 4 1 2 3 155 15 100 93. 6 65. 8 1 2 3 155 15 180 95. 8 69. 0 1 2 3 distilled dirt-$]? 760 84. 0 69. 8 1 2 4 distilled directly 760 89.0 61. 3

Example 57.-Eighteen grams (1.0 mol) of Water and 0.5 g. of copper powder (antipolymerizing agent) were added to 268.5 g. of the reaction product of one mol of ethylene cyanohydrin and two mols of 100% sulfuric acid. The mixture was stirred and heated to 120 C. The heat released by hydrolysis at first-caused the tempera ture to rise somewhat above 120 C. At the end of four hours the mixture was subjected to a pressure of 12-15 mm. and the temperature was raised ultimately to about 195 C. The distillate weighed 61.0 g. Titration indicated a 76.0% yield of acrylic acid (based on the ethylene cyanohydrin used) in a strength of 89.6%.

Example 58.--Use of the same procedure as that described in Example 5'7 except that 36 g. (2.0 mols) of water were employed, gave 85.5 g. of distillate. The yield of acrylic acid was 91.6%, the strength of the distillate being 77.1%,

' Example 59.,Use of the procedure described in Example 57 except that 54 g. (3.0 mols) of water were used, gave 102.2 g. of distillate. The yield of acrylic acid was 93.2% of the theoretical, V the strength of the distillate being 65.6%.

Example 60.-Fifty-four grams (3.0 mols) of Water and 0.5 g. of copper powder were added to 268.5 g. of the reaction product of one mol of. ethylene cyanohydrin and two mols of 100% sulfuric acid. The'rnixt-ure was then heated rapidly to 150-155 C. and held at this temperature, while being stirred, for fifteen minutes. At the end of this period the pressure was reduced to 13 mm. and the temperature was raised, ultimately to 195 C. The distillate weighed 107.2 g. The yield of acrylic acid was 94.8% of the theoretical, the strength of the distillate being 63.6%.

The improved method herein described for the production of acrylic acid possesses many advantages which will be apparent to those skilled in the art. The conversion of ethylene cyanohydrin to c-sulfatopropionamide, the hydrolysis of the amide and the cracking of the hydrolyzed product are smooth, readily controlled reactions. The method is simple and easily operated, and the desired acid is obtained in high yields.

While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not to be limited thereto but is to be construed broadly and restricted solely by the scope of the appended claims.

We claim: 1. A method of preparing acrylic acid which cyanohydrin is reacted with anhydrous-sulfuric acid at a temperature not exceeding about 100 C. 4. A method of preparing acrylic acid which includes the steps of reacting ethylene cyanohydrin with anhydrous sulfuric acid at a temperature within the range of -90 C. to produce ,8- sulfatopropionamide, adding water thereto, heating the mixture at a temperature sufficient to form acrylic acid and ammonium bisulfate, and recovering the acrylic acid therefrom.

5. A method of preparing acrylic acid which includes the steps of reacting ethylene cyanohydrin with anhydrous sulfuric acid at a temperature within the range of 40-90 C. to produce 5- sulfatopropionamide, adding water thereto, heating the mixture under a pressure less than atmospheric pressure at a temperature sufllcient to form acrylic acid and ammonium bisulfate, and recovering the acrylic acid therefrom.

6. A method of preparing acrylic acid which includes the steps of reacting ethylene cyanohydrin with anhydrous sulfuric acid at a temperature within the range of 4090* C. to produce 5- sulfatopropionamide, adding water thereto, heating-the mixture under a pressure less than atmospheric pressure at a temperature sufiicient to form acrylic acid and ammonium bisulfate, and distilling the acrylic acid therefrom.

'l. A method of preparing acrylic acid which includes the steps of heating a mixture comprising p-sulfatopropionamide and water at a temperature sufficient to form acrylic acid and ammonium bisulfate, and recovering the acrylic acid therefrom. 8. A method of preparing acrylic acid whic includes the steps of heating a mixture compris- 11. The inethod of claim 10 in which the ethylene cyanohydrin and. anhydrous sulfuric acid are reacted in molecular proportions.

12. The method of claim 10 in which the reaction takes place at temperatures less than 100 C.

13. The method of claim 10 in which the reaction takes place at a. temperature within the range of 40-90 C.

HAROLD S. DAVIS. MYRL UCHTENWALTER. JOHN G. ERICKSON.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Orthner et a1. 1 Sept. 9, 1941 Trusler Apr. 20, 1926 Ritchie 81; a1 Dec. 9, 1941 Hill Jan. '7, 1936 Crawford etal Dec. 13, 1938 FOREIGN PATENTS Country I Date Germany July 24, 1936 Germany Jan. 7, 1937 

